[FIX] snailmail: do not decode null objects
[FIX] snailmail: do not decode null objects

Prior to this commit, we would try to decode the logo of a company
without any verification on its presence. If the logo was not set, we'd
try to decode nothing which caused a crash.

This commit ensure that we asert that the field is set before trying to
encode it for a JSON payload.

closes odoo/odoo#36784

X-original-commit: f40f763831bace8c499072ea81ef9bbd5fc910e4
Signed-off-by: Nicolas Martinelli (nim) <771435c469f83f6aa9c405ac5e1ed06314a94f2d@odoo.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo